Ultra high frequency signaling



April 11, 1939. G. c. soUTHwoRTH ULTRA HIGH FREQUENCY SIGNALING FiledOct. '7, 1936 5 Sheets-Sheet l /N VE N TOR By G'. C. SOU TH WORTH A TTORNE Y 5 Sheets-Sheet 2 G. C. SOUTHWORTH ULTRA HIGH FREQUENCY SIGNALINGFiled Oct. '7, 1936 .271' n. DEGREE:

April 1 1, 1939.

FIG. 8

u f l 0 v u I l l l l l l 1 1 I l 1 l f 1 1 l l l Q ll 5.504

/N VEA/TOR 6.6. SOUTHWORTH A TTORNEV April ll, 1939. G. c. soUTHwoRTH2,153,728

ULTRA HIGH FREQUENCY SIGNALING Filed OCT.. 7, 1956 5 Sheets-Sheet 3FIG/5 /NVEA/Tof? G C. SOUTHWORTH A TTORNEV API'UL, 1939 G. clsoUTHwoRTHA2,153,728

ULTRA HIGH FREQUENCY SIGNALING Filed Oct. 7, 1936 5 Sheets-Sheet 4 /NVEA/TOR G.C.SOUTHWOR7'H A TTORNEY April 11, 1939- G. c. soUTHwoRTH 42,153,728

ULTRA HIGH FREQUENCY SIGNALING Filed oct. 7, 1956 5 sheets-sheet 5 92).93N 95] 7 WAVE TYPE uve Typs 7 FIG. 2/ 9\ vconn/Eiern? REPEAT"www5/PTH?` 95) A TTORNEV o Fig. 3 is .Patented Apr. lul, 1.91939 ULTRAHIGH FREQUENGY SIGNALING George Clark Southworth, Red Bank, N. J., as-

signor to American Telephone and Telegraph Company, a corporation of NewYork Application October'el, 1936, Serial No. 104,524

ss claims.

This invention relates to new and improved methods and means for ultrahigh frequency signaling. More specifically it relates to guided wavesin a dielectric medium of limited boundaries and is a continuation inpart of my application, Serial No. 73,940, filed April 11, 1936, whichissued as U. S. Patent 2,106,771, February 1, 1938.

A general object of the invention is to provide means for applyingvacuum tube technique to such dielectrically guided wave systems, havingin mind the difculties arising with the use of such high frequencies asare contemplated with dielectrically guided waves.

l5 One specic object of the invention is to provide circuit arrangements.using vacuum tubes of special design which will avoid suchdifficulties.

Another object of the invention is to provide amplification or othervacuum tube operations '20 for such wave systems with appropriateimpedance matching and with volume control.

Still further objects are the association of amplifiers with dielectricguides or sections of dielectric guides for amplification in a mannerwhich eliminates effects due to non-linear characteristics ofamplifiers, for multiplex signaling, for modulation of guided waves,vand for generating high frequency oscillations of definite frequenciesappropriate to such signaling systems.

All these objects and other objects and advantages ofmy invention willbecome apparent upon the consideration of a limited number ofillustrations of my invention presented in the following specication andaccompanying draw- The invention relates to such dielectrically guidedwaves as are described in my patent application Serial No. 661,154,filed March 16, 1933 which issued as U. S. Patent 2,129,711, Sept. 13,1938 and other related applications.

Referring to the drawings: Fig. 1 shows a special design of vacuum tubesadapted for carrying out my invention;

Figs. 1A to 1D show forms of grid structure for use in such a vacuumtube and adapted in some cases to be selectively responsive to certaintypes of dielectrically guided waves;

Fig. 2 is a simple form of amplifier circuit embodying a portion of myinvention;

modification of the circuit of Fig. 2; Fig. 4 shows a modification ofthe tube of Fig. l;

Fig. 5 is a conventional showing of the vacuum tube amplifier of Figs. 2and 3 which will be used in many of the figures;

other grid performs a similanfunction.

- Figs. 6 to 9 show steps of further development of the basiccircuit ofFig. 2;

Fig. 10 shows my invention adapted for a pushpull circuit;

Fig. 11 shows my invention applied to a sys- 5 tem for two-waysignaling;

Figs. 12 to 15 are different views of an amplifying circuit for two-waysignaling on the same carrier frequency;

Figs. 16 to 21 relate to other modifications oil ln my invention;

Figs. 22 to 24 illustrate the application of amplifier tubes forgenerating ocillations in sections of dielectric guides; and

Figs. 25 and 26 show arrangements for obtainl5 ing modulation.

As pointed out in my copending application Serial No. 661,154 referredto above, there are several different types of Waves that may bepropagated through dielectric guides. These call for 20 differentarrangements of apparatus associated with the guideA in rder to betteraccommodate each of these waves. As regards the arrangements of the waveguides themselves, however, the fundamental principles are much the same25 for all types of waves. These principles can be illustrated by thespecic examples chosen below which center around the so-called Hi 4typeof wave but the application to different es of waves will be apparent tothose skilled in the art. $0

One of the limitations to the use of ordinary vacuum tubes as amplifiersof extremely high frequency is anuncontrolled coupling between the gridand the plate circuits that results from the priximity of the grid andplate circuits in the glass seal and other parts 'of the tube. Animportant feature of my invention as it relates to vacuum tubeamplifiers resides in a vacuum tube of special design in which a verycomplete shielding of the output circuit from the input 40.

circuit is provided whereby undesired coupling between the two circuitsis reduced t o a low value. y The tube may be either a triode or Vamulti-grid tube. In the rst case the grid is a perforated metal septumthat divides the tube into separate 45 chambers. In the other the screengrid or some The metal `.septum comprising the grid extends through thewalls of the glass envelope and is suciently large that if necessary itmay be 50 soldered or otherwise connected into a metal sheet ofconsiderable expanse. By this means the two halves of the tube may beplaced in separate compartments or chambers with no appreciable couplingexcept the electron flow through the grid'and the very small amount ofcapacity effect through the meshes of the grid or screen.

One arrangement of the special tube is shown in Fig. 1 in which II andI2 are two halves of a glass envelope which is more or less spherical inshape. These are separated by a metal septum I3 extending from the wallsof the glass envelope sufficiently far to be electrically connected intoa still larger metal sheet when necessary. The septum is perforated asshown in Fig. 1A so as to function as a grid through which electrons maypass. Lines of electric force on the other hand do not readily extendthrough these meshes except perhaps those associated with or attached tospace electrons. A source of electrons IS, which in this case lis aheated cathode, and also a plate I1 are located on opposite sides of thegrid. The lead wires I4 and I5 to the cathode and plate, respectively,should preferably approach from diametrically opposite directions andpreferably both are perpendicular to the plane of the grid I3.

The grid may be perforated by a series of circular holes as illustratedin Fig. 1A or it may consist of square or other shaped openings, such asmight result from a basket weave of metallic wires.

Fig. 1B shows a form of grid structure that is particularly adaptable tothe so-called H1 type of wave. When the metallicwires I3b of the gridare parallel to the transverse lines of electric force, little or noelectric induction will take place through the grid from the inputcircuit to the output circuit or from the output back to the input. Whenthey are perpendicular considerable induction will result. Thus theamount of feedback is controllable to a considerable extent. Atintermediate angles only a moderate induction will take place. Forsimilar reasons it will be apparent that the grids of Figs. 1C and 1Dare adaptable for shielding against Ho and Eo types of wavesrespectively. In Fig. 1C the metallic wires comprising the grid are inthe form of concentric rings I 3c maintained in position in the apertureof the septum I3 by supporting structures I3s. In Fig. 1D the metallicwires comprising the grid are disposed radially as indicated at I 3d.Recalling that in a symmetric magnetic or Hu type wave the lines ofelectric force are circular, coaxial with the guide and transverse tothe axis thereof, andA that in a symmetric electric or Eo type of wavethe electrical eld has a radial component, it is evident that the gridwires in Figs. 1C and 1D conform with these electric fields of the Hoand E0 types of waves, respectively.

Fig. 2 shows in schematic form a longitudinal section of two cylindricalcompartments connected together by one of the vacuum tubes illustratedby Fig. 1. Here the sections of the two cylindrical compartments whichcomprise the adjacent ends of two dielectric guides are shown asoverlapping and having a boundary in common. The grid I3 of theamplifier is placed across an aperture in the common boundary andconstitutes a portion of that boundary. The filament I6 is placedadjacent to the grid member in the incoming guide section 2| and theplate I1 is similarly placed in the outgoing guide section 22. The leadWires to the plate and filament pass through insulating bushings set inthe walls of the guide, thus preventing short-circuiting the directcurrent or low frequency components flowing in the wires. Small by-passcondensers I8 and I9 prevent the high frequency waves residing in theguide from escaping through the bushings to the exterior. These by-passcondenscrs may take on a variety of forms, being representedconventionally in Fig. 2. Ordinarily it would be sufficient to have asmall metal disc attached to each terminal and separated from the guideby a thin layer of dielectric, such as mica, or to have a metal sleeveconnected to the guide wall and enclosing the lead or leads as in Fig.4. In the i1- lustrations that follow both bushings and the bypasscondensers will be omitted for purposes of simplification. Y

Waves, originating in a wave generator such as G of Fig. 2, advance fromthe left to the right in the cylindrical metal chamber 2| whichcomprises the incoming end of the dielectric guide, the dielectric guidein this case consisting preferably of a metal tube filled with a lowloss dielectric which may be air. For H1 waves a voltage differenceexists between the top and bottom of the chamber 2| and the lines ofelectric force as they progress impinge upon the filament leads. By thismeans the voltage difference is communicated to the small space betweenfilament I6 and grid I3. This will tend to either increase or decreasethe electron flow between the filament and plate depending upon thepolarity of this instantaneous voltage. The change of electron flowextends across the space between grid I3 and plate I'I and this inducesin chamber 22 of the outgoing guide a new electromotive force and,consequently, a new set of waves, in general` of highzelr amplitude thanthose prevailing in chamber Fig. 3 shows a modification of thearrangement of Fig. 2 in that the two sections of guides are arranged inabutment with the grid serving as a complete electrical separationbetween the two abutting sections except for such coupling as may occurthrough the grid mesh. In this figure the filament or electron source isadjacent to the grid on the incoming side and the plate on the outgoingside. Whereas the arrangement of Fig. 2 is particularly adapted to theH1 type of wave, although applicable to other types of waves, thearrangement of Fig. 3 is particularly suitable for the Eo type of wavein which the electric lines of force are radial. By means of theconductors 20 and 20a running out from the lament and the platerespectively such a type of wave is readily received from the incomingsection on the lament and readily launched in the outgoing section, asWill be understood by reference to my copending application Serial No.701,711, filed December 9, 1933 which issued as U. S. Patent 2,129,712,September 13, 1938. The arrangement of Fig. 3 lends itself well to theuse of a grid of one form or another, such as shown in Figs. 1A to ID,whereby the input and the output. will be effectively shielded from eachother. 'Ihe grids of Figs. 1C and 1D will suppress feedback of Ho typeand Eo type of waves respectively to a very high degree, While at thesame time tending to pass the En type and the Ho type of waverespectively.

While the filament and plate leads for the amplifier of Fig. 3 may bebrought in through bushings with suitable by-pass condensers at avariety of points, it is desirable that this should be done at pointswhere the variation in the electric field are a minimum and such pointscan be established by setting up standing waves which provide nodalpoints for the electric field. Such standing waves may be produced inthe neightential node at the disc 39 reinforcing the potentialvariations on the plate and serving as a suitable point from-Which totake ,the plate lead. The quarter wavelength distances referred to mayhave to be appreciably altered when the capacities between the tubeelements are substantial.

The circuits of Figs. 2 and 3 have been described primarily in terms ofa triode amplifier but as indicated earlier this tube may be a multigridtube. In this case the arrangement might very well be that shown in Fig.4 in which three grids are shown. One of these would, in geni eral, bean integral part of the guide wall and the grid which are notpredictable in advance.

others would be insulated therefrom for. direct f current effects butwould be associated to any degree desired for highv frequency effectsthrough small capacities as indicated. These grids may be used in anyorder and in any such manner as is now well vunderstood in connectionwith multi-grid tubes; being adapted through suitable leads to receiveany .direct current voltagedesired. These leads would be insulated fordirect current but not for alternating current effects just as for thefilaments and plates. The septa of the various grids may extend as farout in various directions as may be desired in the light of theparticular wave-lengths and particular wave types to be amplied.

Hereinafter for purposes of simplicity the ampliiler will be shownconventionally as in Fig. 5 and, in general, the two sections of guideswill be shown as overlapping, but itis to be -understood that in theinvention either of the arrangements of Fig. 2. or 3 may be used and atube of one form or another with a grid or grids of one form vor anothermay be used, some of which tubes will be described in detail below. Inall cases, except where otherwise described, the elements of thedischarge device are enclosed within an envelope that is sealed to thegrid septum as illustrated' in Fig. 1.

In order to increase substantially the voltage impressed betweenfilament and grid the distance between the filament I6 and the end wall23 of Fig. 2is made substantially one-fourth of the wave-lengthprevailing in the chamber 2|. In a similar way the distance between theplate lead i1 and the end wall 24 of chamber 22 is made one-fourth ofthe wave-length prevailing in that chamber. When the latter conditionhas been met waves which pass to the left in chamber 22 will bereflected back in phase with those being propagated to the right.Neither of these dimensions can be specied precisely asbeing onefourthwave-length .for there are capacity and other effects associated withthe filament `and In practice, therefore, -it is advisable to have theseend plates take the form of movable pistons which may be adjusted to amaximum of amplified output or they may be adjusted to give any smallerdesired amplified output. Such pistons are shown in Fig. 6.

A thermionic vacuum tube possesses both reactance and resistance andlike other circuit elements operates best into its own characteristicimpedance. Methods for approximating such impedances are disclosed in mycopending application, Serial No. 73,940, referred to above and also inan application of King and Bowen, Serial No. 62,616, filedFebruary 6,1936. In Fig. 6there is shown in longitudinal section an amplifierarrangement in which such an impedance match may be accomplished. Thewave guide 2| terminates in the chamber 3l containing the gridfilamentinput to the amplifier. This chamber is bounded longitudinally by themovable piston 32 and the iris 33 which is adjustable as to size ofaperture and position. Under these conditions the distances from thenlament to iris and fllament to piston, as-well as that from iris topiston,

-can be adjusted as desired. By proper adjustment of thesedistancesthere will be a maximum power impressed between the filamentand grid and a minimum of standing waves in the wave guide 2l.

In precisely the same way that the input impedance may be matched to thewave guide to which it is connected so may the plate output of theamplifier also be matchedV to the guide 22. This latter is ,accomplishedby means of the chamber 34 bounded by the movable piston 36 and movableiris 35.

It will be observed that the two chambers 3| `and 34 of Fig. 6 areentirely divorced except for the coupling that may take place throughthe grid i3. Although this coupling will, in general, be small there maybe conditions where it is sufficient to cause regeneration or possiblyoscillations in the amplifier system. When such effects are not wantedthey may be eliminated or controlled to the desired limit in the ampliershown in' Fig. 1. This arrangement is substantially the same as that ofFig. 6 except that an adjustable iris 40 is placed in the wallseparating chambers 3i and 3l. This iris permits a small amount 'of theamplified output resident in chamber 34 tov escape back into chamber 3ito be combined with that about to be ampliiied. By so placing thisorifice that the total distance from plate to oriice 40 and from orice40 to the filament is the equivalent of a half wave-length or anymultiple thereof, it is evident that there will be impressedY may becontrolled. Such a device, therefore, permits by appropriate adjustmentof the following (l) complete neutralization (2) negative regeneration(3) positive regeneration and (4) oscillation.

Although the amplifier thus far shown discloses but one tube, two ormore tubes connected for parallel operation could be used. Such anarrangement is shown in Fig. 8 in which two such tubes are shown,provision for proper phase reinforcement being made by so spacing thetubes' that they are located 366, 720, etc. electrical degreesapa'rt.Anti-singing coupling between the Thus far nothing has been saidregarding the cross-section of the guide sections 2| and 22. It is to beunderstood, however, that these sections, as well as the overlappingportions, may have any desired cross-section, such as a circular one ora rectangular one. There would be certain advantages in having arectangular cross-section, especially in the portion where there isoverlapping of the two sections.. Also there is the implication that theguide 2| and the chamber 3| are of the same cross-section and that thechamber 3| is indeed but a continuation of the guide 2|. The invention,however, is not to be limited in any such respect. Thus, Fig. 9 shows anarrangement in which the guides 2| and 22 may be circular incross-section and the overlapping portions taken together are circularof the same dimensions with a diametral partition so that the chambers3| and 34 are semi-circular in cross-section with a grid lying in thediametral septum. Semi-circular pistons 32 and 36 would perform the samefunction as the pistons of the previous figures.

- Fig. 10 shows a push-pull combination of two tubes arranged as acircuit for amplification. Waves to be amplified adva'nce from the leftin the wave guide 2| into the bifurcated resonant chamber bounded by theadjustable iris 33 and the piston 32. This chamber also contains as apart of its Wall the grids I3 and I3' and also filaments i6 and IB oftwo independently connected vacuum tubes. By proper adjustment of theiris 33 relative to the piston 32 and the lilaments I6 and I6 a desiredportion of the input power may be impressed on the vacuum tubes inaccordance with the principles already set forth. The correspondingoutput circuits of these tubes are tuned for an optimum by means of thepistons 36 and 36' and the irises 35 and 35', respectively. The outputof this amplifier combination is led away through the wave guide 22.

When the arrangement of Fig. 10 is used with the H1 type of wave it actsin the push-pull manner to balance out effects of non-linearity in thecharacteristics of the tubes, the grids I3 and I3' receiving oppositepotentials with respect to their filaments. If, however, the incomingwave is of the En type with radial lines of force, then the potentialsof the grids are varied together and the structure behaves as one of twotubes connected in parallel. It will be evident also that in this Fig.10 the plates and filaments may be interchanged. In that event, therelative directions of input and output are reversed. Obviously, themethod of neutralization disclosed in connection with Fig. 7 may beapplied here also.

Fig. 1l discloses a method of amplifying two bands of oppositelydirected Waves propagated in the same long wave guide. These might, forexample, be different channels of television. In general, it isdesirable that these two bands should differ in frequency. They may bedesignated respectively f1 and f2 with the understanding that eachrepresents a fairly broad band of frequencies appropriate for whateversignal is to be transmitted. 'I'he group of frequencies designated as f1is propagated from left to right. At 4| it meets a bifurcation in theguide. The upper chamber bounded by iris 33 and piston 32 is so tuned asto readily accept this group of frequencies, whereas the lower chamberbounded by the iris 33' and the piston 32' tends to reject this band. Itis true also that there is little tendency for such waves to pass beyondthis chamber, since here they encounter the plate circuit of a vacuumtube instead of a grid circuit. The band of frequencies .f1 resonant inthe chamber 42 is ampliiied and passed into the chamber 43 in accordancewith principles already set forth and finally into the wave guide 32where it is propagated to the right.

The group of frequencies fz arriving from the right similarly passesthrough chamber 42 which is tuned to that group, and thence into asimilarly tuned chamber 43 and nally into the wave guide where it ispropagated to the left. Thus, there is provided means for transmissionfrom West to east and from east to west through an amplifying pointWithout interference between the two bands of frequencies,

Figs. 12 to 14A disclose a two-way repeater similar to that of Fig. 11except that the oppositely directed channels of communication mayconsist of similar bands of frequencies polarized in different planes,preferably at right angles to each other. These opposite or diierentstates of polarization enable the two channels to be segregated forpurposes of amplification. In Fig. 12, the group of frequencies enteringchamber from the left may be regarded as having the electric forces inthe plane of the drawing. In addition there is another channel, usingthe same range of frequencies, leaving this chamber to the left. Theelectric forces of the latter are perpendicular to the plane of thedrawing and, therefore, do not interfere with the first.

The rst group of frequencies entering from the left is amplified andpassed into chamber 52 and thence into chamber 53 through a parallelwire grating 56 or other suitable polarizing means Shown in Fig. 12A,which grating is disposed at right angles to this electric force. Thisamplified wave is then propagated to the right along the wave guideconnected to chamber 53 as appears in Fig, 14.

The wave train for the second channel of communication arrives along thelast-mentioned wave guide into a chamber 53. It has its plane ofpolarization at right angles to the rst wave and, consequently, isunable to enter chamber 52 because of the orientation of the wires ofthe grating 56. It may, however, pass through the wires of grating 51into chamber 54 from which it passes, after ampliilcation, into chamber5|, whence it is propagated in the wave guide leading to the left, allas is seen from inspection of Figs. 12 to 14. 'I'he external appearanceof a group of rectangular guide sections is shown in Fig. 15.

In the interest of simplicity gratings of parallel wires have beenassumed. Alternate and perhaps more effective means may be had by usingeither parallel plates as gratings or short sections of rectangularguides, In the latter case one of the dimensions is made so small as todiscriminate markedly against the undesired components.

While the amplifiers of Figs. 2 and 3 will be responsive, to some extentat least, to any type of guided wave, they are particularly adapted forcertain types of waves. Thus Fig. 2 lends itself especially well to boththe H1 and Eo type of waves and the arrangement of Fig. 3 lends itselfparticularly well for the En type of waves. Furthermore, it is possibleto design other tube arrangements, particularly well adapted for stillother types of waves. Thus Fig. 16 shows a tube design for Ho waves.

Referring more particularly to Fig. 16, there is shown Va cross-sectionof a portion of the guide system including the amplifier. The metalboundary 80 together with the radial planes. all shown in transversesection, divide the guide into octants' a vacuum tube of the typealready described. The latter is so connected that the normal electronllow in the four tubes progresses in the same `circumferentialdirection, that is, clockwise as illustrated. They radial conductingplanes between 62 and E3, etc. serve not only as dividing planes betweenthe different amplifiers but also as convenient points for bringing inthe respective filament and plate leads through suitable bushings andby-pass capacities. T'he arrangement thus results in alternatecompartments containing lament and grid and grid and plate.- These maythen be regarded as input and output circuits of the amplifiers inparallel with the input and output circuits nearly completely shieldedfrom each other.

`Each compartment is bounded axially by a sector shaped piston (notshown) and an iris diaphragm shaped either asA shown in Fig. 17 or 18.

` The compartments are so arranged that the irises of the input chambersface in one direction and the irises of the output chambers face in theother. These effectively isolate the input from the output circuits andat the same time are positioned to give the tuning described inconnection with previous iigures. It will be evident that the chambers6| and 62 are roughly equivalent to chambers 3| and 34 of Fig. 6.

'I'he opening of the sectored irises may be made adjustable as shown inFig. 19 where two substantially similar sectors are made to overlap tosuch extent as desired, thus controlling the size of the iris aperture.It is evident that the compartments of Fig. 16 may be sectors as shownor may be altered to be triangular, rectangular or even circular incross-section without materially altering thebehavior of the device.

Fig. 20 shows still another form of tube which may be connected to beparticularly eiective for the En type of waves'. Here the incoming guide1I with a section of axial conductor 12 brings the incoming wave to theinput circuit of the vacuum tube comprising the cathode 14andcylindrical gridv I3, the cathode 14 being heated in any suitablemanner, such as by the heater element 15. The plate circuit of this tubecomprises the cathode 14 and the outer cylindrical sleeve 11 which thencontinues and becomes the outgoing guide 18, there being provided againthe section of axial conductor 19 to assist in the.launching of theoutgoing wave. As is clearly seen from the figure the container for thevacuum tube comprises the metal sleeve 11 and the insulator portions 80which may be of glass or other suitable material.

AIt is desirable in this as in the previous cases to tune the input andoutput circuits. For the input circuit this is accomplished by theannular piston 8| and the iris 82. For the output circuit this isaccomplished by the annular piston 83 and the iris 84.

In either Fig. 16 or 20 the details of the grid structure may be variedin the light of the particular type of wave being repeated as will beevident from the disclosure in connection with Figs. 1A to 1D. h

lIn all these modifications of tubes it is to be observedl that the gridserves to divide the vacuum tube into. two chambers which aresubstantially shielded from each other.

While, as already pointed out, any one of these amplifiers with any formof grid will be receptive I degrees than 180, 540, etc. electricaldegrees.

to some extent to all types of waves, each one is particularly welladapted for a special type of wave. Much latitude, however, islpermissible as going guide 96 or it may ilrst be impressed on la wavetype converter 95, -which converter mayV restore the wave to theoriginal type or to any other desired type. This feature of convertingone wave type into another is fully disclosed in my copendingapplication. Serial N0. 701,711-Ieferred to above.

While this invention has been described'thus far primarily in connectionwith amplification of al wave dielectrically guided from one terminal toanother, thev particular 'type of tube described and other principlesshown can be eiectively used for generating high frequency oscillationsin which a primary factor is the presence of a suitable amplifier.Circuits of this kind will now be described. Referring to Fig. 22, thereis shown a modification of the apparatus of Fig. 7 rendering itparticularly suitable as an oscillator or generator of electric waves.One requirement for oscillations is that the conditions forneutralization previously mentioned be avoided. Two adjacent sections ofdielectric guide are provided and in this case they are shown asoverlapping with a common boundary between the compartments formed bythese two sections and certain movable pistons. A vacuum tube. am-

-plier with the input and the output circuits respectively in these twocompartments is provided in the manner already described. Ari iris 40provides coupling between the plate and the grid circuits, the positionof this iris being such that thephase diierence over its path betweenelectric forces in the gridcircuit and in the plate circuit should benearer 0, 360, 720, etc. electrical In addition pistons 33 and 36 areprovided thereby preventing any radiation from escaping by these routesand at the same time tuning the chambers to the frequency to begenerated. .This necessitates the provision of a power outlet consistingof a section of Wave guide 62. The output into the section 62 may b econtrolled by an adjustable iris 6I, the best location and theadjustment of this iris being such as to provide a good load impedancefor the tube to operate into. Obviously it would be possible to combinethe outlet 62 and the piston 33.

Fig. 23 shows a further modication of this fundamental circuit wherebytwo or more thermionic tubes located 360 electrical degrees apart mayeffectively be operated in parallel to increase the power.

Fig. 24 shows how'two or more thermionic tubes oppositely directed maybe located at intervals of 180 electrical degrees to give increasedpower. While in this latter ligure a coupling iris is shown, such aniris would not be necessary so far as merely setting up oscillations areconcerned. If, however, the tubes are of substantially the same powerthen the power density in the chamber containing no outlet would becomeexcessively high. Such an iris as shown at 40 is therefore desirable asproviding means for oscillatory power to leave that chamber and passdown to the outlet 62. On the other hand, one of these tubes, say theone with the plate I1, might be a low power tube providing only aboutsuiiicient energy in its output circuit to take care of the lossesinherent in its chamber. In general, it will be seen that it is notnecessary that the tubes be of the same power output.

The principles set forth above and the apparatus described lendthemselves effectively for the use of both the amplification and themodulation functions of the vacuum tube amplifier. This is illustrated,for example, in Fig. 25 which permits modulation or harmonic generation.When so used the vacuum tube should be operated on a portion of itscharacteristic possessing curvature and this would ordinarily beaccomplished by the use of a substantial negative bias applied to thegrid. Such a biasing, by a battery or otherwise, is for simplicityomitted from the drawing but it is obvious that the grid would beinsulated for direct current effects from the common metallic boundarybetween the overlapping chambers by means of such arrangements as areshown in Fig. 4. The direct current biasing voltage would then beprovided through suitable bushings with small by-pass condensers asalready explained. As is well known, a tube so biased and operating onthe non-linear portion of its characteristic yields various modulationproducts including, in general, the sums and differences of allfrequencies impressed on the grid circuit, as well as their respectiveharmonics.

In Fig. 25, for example, We may assume that there is impressed on thegrid I3 two frequencies f1 and f2 coming from diiierent directions asindicated by the arrows. 'Ihese frequencies might, for example, berespectively 1750 megacycles and 2000 megacycles. There will then beproduced in the plate circuit I1 all of the components mentioned abovebut by proper adjustment of the piston 36 and the iris 35 it is possibleto select any one of these components, such, for example, as the sum ofthese frequencies or 3750 megacycles, which component will then bepropagated in the wave guide 22.

It is to be understood, of course, that the frequencies represented byf1 and ,f2 may either or both be single frequencies or bands oflfrequencies. 'Thus the one might be a single or carrier frequency andthe other a band of frequencies with which the carrier is to bemodulated.

If a single frequency of say 2000 megacycles were impressed on thefilament grid circuit various harmonics would, in general, appear in theoutput. By a proper adjustment of the iris 35 and the piston 36 onecould select the several harmonics to the exclusion of the fundamental.Furthermore, by an appropriate restriction of the diameter of the outputchamber circuit all harmonies below a certain order would be rejected.The principles by which such selection is made is described fully in mycopending application Serial No. 745,457, filed September 25, 1934 whichissued as U. S. Patent 2,106,768, February 1, 1938.

Fig. 26 shows an alternate method of producing modulation involving theplate circuits of two tubes. In this case the input frequencies or bandsof frequencies f1 and f2 are shown as coming in on independent waveguides, each such wave guide containing the input circuit of anampliiier of the type already described. The output circuits of thesetwo tubes are both contained in a common output wave guide and, in-

asmuch as these two output circuits react upon each other, there willappear the sum and difference frequencies. By the appropriate use ofadjustable pistons and irises any one of these output components may beselected for propagal tion in the output Wave guide.

While this invention has been described in terms of. a limited number ofspecific applications, it is to be understood that many variations arepossible. Thus, it is possible to make use of the nearly completeshielding between the input and output circuits'of the thermionic tubesto launch the outgoing wave in a manner largely independent of theincoming wave. For example, on referring to Fig. 2, it is noted ,thatthe plate lead is shown as lying in the plane of the drawing and it wasstated that if the incoming wave is of the H1 type with the electricvector in the plane of the figure that the outgoing wave will be of thesame form with the same plane of polarization. However, it should bepointed out that by changing the direction of the plate lead theoutgoing wave, while still of the H1 type, will be launched with itsplane of polarization rotated with respect to the plane of polarizationof the incoming wave.

Also, in connection with both Fig. 2 and Fig. 3, it will be apparentthat a wide latitude is pei'- missible in reshaping the outgoing waveeither in plane of polarization or in type of Wave, all oi which will beevident by reference to my copending application 701,711 mentionedabove.

While this invention has been described chiefly in terms of metallicallyshielded dielectric guides it is to be understood that it is alsoapplicable to unshielded guides of various forms.

What is claimed is:

1. In a dielectrically guided wave system, a hollow guide fortransmitting the waves, and means for amplifying the waves comprising anamplifier with an input and an output circuit contained within theguide.

2. In a dielectrically guided wave system, means for amplifying thetransmitted wave comprising an amplifier with an input and an outputcircuit, the said circuits being shielded from each other except for thecoupling through the grid.

3. In a dielectrically guided wave system, a hollow Wave guide fortransmitting the waves, and means for amplifying the waves comprising anamplifier with an input and an output circuit contained within theguide, the input and the output circuits being shielded from each otherexcept for the coupling through the grid.

4. In a metallic pipe guide, a repeater comprising a three-electrodevacuum tube within the guide, means on one side to apply theelectromotive force of incoming waves within the guide across theCathode and grid of said tube, and means on the other side to radiateinto the interior of said guide lines of, electric force from across thecathode and plate of said tube.

5. In combination, a metallic pipe guide, a repeater therein, means onthe input side to match the input impedance of the repeater to theimpedance of the guide, means on the output side to match the outputimpedance of the repeater to the impedance of the guide, and anadjustable feedback connection to neutralize any oscillatory tendency inthe repeater.

6. In combination with a dielectric wave guide made up of two adjacentsections, a space charge device comprising a cathode within one section,an anode within the other section and a control element lying in theboundary between the two sections. e

'1. In combination with a dielectric wave guide comprising twooverlapping hollow metal sec- A tions, a device for repeating andamplifying the wave from one guide section to the second section, saiddevice comprising a cathode near the end of one guide section at theoverlapping end,

an anode in the overlapping end of the second section and a gridelectrode lying in the boundary between the two overlapping sections.

8. The combination of claim 7, characterize by the fact that the gridelectrode is so shaped and positioned as to permit selected types oi'dielectric waves to pass through.

9. The combination of claim 7, characterized by the fact that the gridmember is connected metallically with the boundary of the guide wherebythe input region and the output region of the repeating device areshielded from each other except yfor the grid portion.

10. In combination with a dielectric wave guide made up of two adjacentsections,l a space charge device, comprising a cathode within onesection, an anode within the other section, a conductive partitionbetween the two sections with an aperture therein, and a grid elementplaced in said aperture.

1l. In combination with a dielectric wave guide made up of two adjacentsections, a space charge device associated therewith, comprising acathode, an anode and a grid element, a conductive partition lying inthe boundary between the two sections, and an aperture in said boundary,one of the elements of the space charge device occupying the saidaperture.

12. The combination 'of claim 10A characterized by the fact that thegridI element comprises a mesh structure so configured with respect tothe electric eld configuration of a particular type of guided wave as torender the space charge device selectively responsive-to that particulartype of guided wave. Y

13. In combination with a dielectric wave guide made up of two adjacentsections, a vacuum tube amplifying device associated therewith,compris-l ing a cathode within one section, an anode within the othersection, and a grid element lying in the boundary between the twosections, the grid element having a mesh of such conguration withrespect to the electric eld configuration of a particular type of guidedwave as to render the amplifying device selectively responsive to thatparticular type of guided wave.

14.. In combination with a dielectric wave guide made up of two adjacentsections, a space charge device comprising a cathode within one section,an anode within the other section and a control element lying in theboundary between the two sections, and a common boundary element betweenthe two sections, shielding the two sections each other electricallyexcept for the control element. L

15. In a dielectric wave guide system, means for amplifying wavestraveling in the guide, said means comprising two sections ofoverlapping guides, and an ampliiier consisting of a cathode in theoverlapping end of the incoming section, an anode in the overlappingportion of the outgoing section and a grid element between the cathodeand anode lying in the plane of the boundary common to the twooverlapping ends.

16. In a dielectric guide system, means for amplifying waves travelingin the guide, said means comprising two sections of adjacent guides 18.The combination of claim 15, characterized by a metallic reector atthefree end ofthe overlapping outgoing section, the reiiectorbeingpositioned to give reinforcement tothe output wave.

19. The combination of claim 15, characterized by the fact that there isa reflector` at the free end of the incoming section and a reector atthe free end of the outgoing section where these sections overlap,therreflectors being positioned to reinforce the potential variations inthe input circuit and in the output circuit of the amplifier.

20. In a dielectric wave guide system, two overlapping sections ofmetallically bounded dielectric guides, a vacuum tube amplifying devicebetween the two sections with the input circuit in one section and theoutput circuit in the other section, and a movable reflector at theoverlapping free ends of the guide sections.

2l..The combination of claim l5, characterized by "the fact that thereis an aperture in said boundary to yield a feedback coupling from theoutput to the input circuit.

22. In a dielectric wave guide system, two overlapping sections ofmetallically bounded dielectric guides, a. three-element amplifyingdevice between the two sections with the input circuit in one sectionand the output circuit in the other section, a reflector at theoverlapping fr-ee end of the incoming section, `and a reactor in theincoming guide in front of the input circuit of the amplier, the.position and reactanceA of the reactor being such as to give impedancematching between the incoming wave guide and the input circuit oftheampliiier.

23. In a dielectric wave guide system, two overlapping sections ofmetallically bounded dielectric guides, a three-element amplifying.device between the two sectionswith the input circuit in one sectionand the output circuit in the other section, a reflector at theoverlapping free end of the outgoing guide section, and an apertureddiaphragm following the anode of the amplifier, the size of the apertureand the position of the diaphragm being suchvas to give matching betweenthe impedance of the output circuit of the vacuum tube and the impedanceof the outgoing guide section.

24. In a dielectric wave guide system, two overlapping sections ofmetallically bounded dielectric guides, a three-element amplifyingdevice between the two sections with the input circuit in onesection'and the output circuit in the other section, adjustable metallicreiectors at the overlapping free ends of the incoming and outgoingguide sections, the reflectors being positioned to produce maximumpotential variations across the input and across the output circuits ofthe amplier, and an apertured diaphragm in the incomingV guide sectionand an apertured diaphragm in the outgoing guide section, the size ofthe apertures and the positions oi the diaphragms being adjusted to givematching between the impedance of the incoming guide section and theinput circuit of the amplifier and to give matching between theimpedance of the output circuit of the amplifier and the impedance ofthe outgoing guide section.

25. The combination of claim 24, characterized by the fact that there isa coupling aperture in the boundary between the two overlappingsections.

26. The combination of claim 24, characterized by the fact that there isa coupling aperture in the boundary between the two guide sections, thesize of the aperture and its position being such as to give desiredmagnitude and desired phase of coupling between the output and inputcircuits.

27. The combination of claim 15, characterized by the fact that there isa coupling aperture in the boundary common to the two guide sections,the aperture being so positioned as to give antisinging coupling betweenthe output and input circuits of the amplifier.

28. 'I'he combination of claim 24, characterized by the fact that thereis a coupling aperture in the boundary common to the two guide sections,the aperture being so positioned as to give antisinging coupling betweenthe output and input circuits of the amplifier.

29. In a dielectric wave guide system, means for amplifying waves guidedin said system, said means comprising a bifurcation in each guidesection meeting at the amplifying point, the bifurcated ends of onesection overlapping the bifurcated ends of the other section, and avacuum tube amplifier associated with each overlapping portion, theamplifiers each being of the form described in claim 15.

30. In a dielectric wave guide system. means for amplifyingoppositely-directed waves guided in said system, said means comprising abifurcation in each guide section meeting at the amplifying point, thebifurcated ends of one section overlapping the biiurcated ends of theother section, and a vacuum tube amplifier in each overlapping portion,the amplifiers each being of the form described in claim 15, the freeends of the guide sections being closed by reflectors so adjusted inposition as to give maximum reinforcement of potential variations in allinput and output circuits.

31. In a dielectric wave guide system, means for amplifyingdielectrically guided waves transmitte'd through said system in mutuallyopposite directions and in respective frequency ranges, said meanscomprising a bifurcation in each guide section meeting at the amplifyingpoint, the bifurcated ends of one section overlapping the bifurcatedends of the other section, and a vacuum tube amplifier in eachoverlapping portion, the amplifiers each being of the form described inclaim 15, there being an apertured diaphragm in front of each inputcircuit and an apertured diaphragm following each output circuit, thesize of each aperture and its position being such as to give impedancematching between the incoming guide section and the input amplifiercircuits and matching between the impedance of the output vacuum tubecircuits and the impedance of the outgoing guide sections.

32. In a dielectric wave guide system adapted for transmission ofdielectric guided waves in both directions but of different frequencies,a repeater point in said guide system comprising a bifurcation of theadjacent ends of the guide at the repeater point, the bifurcatedsections being in overlapping relationship providing two parallel wavepaths, and a vacuum tube amplifier of the type described in claim 15 ineach path, one amplifier pointing in one direction and the otherpointing in the other direction, whereby signals from east to westtravel through and are amplitied in the one path and signals from westto east travel through and are amplified in the other path.

33. In an oscillation generator of high frequency, two sections ofmetallic tubing adjacent to each other and with a common lateralboundary between the sections, and an amplier with an input circuit inone of the said tubes and an output circuit in the other tube, the gridmember being in the plane of a portion of the boundary common to the twotubes.

34. In an oscillation generator of high frequency, two sections ofmetallic tubing overlapping and with a common boundary in theoverlapping portion, a vacuum tube with an input circuit in one of thesaid tubes and an output circuit in the other tube, the grid memberbeing in the plane of a portion of the boundary common to the two tubes,and reiiectors at the ends of each section positioned to give resonancefor the frequency to be generated.

35. In an oscillation generator of high frefrequency, two sections ofmetallic tubing overlapping and with a common boundary in theoverlapping portion, a vacuum tube with an input circuit in one of thesaid tubes and an output circuit in the other tube, and a grid member inthe plane of a portion of the boundary common to the two tubes, and anapertured coupling between the two tubes in the boundary common to bothand so positioned as to give singing phase relationship between theoutput and input circuits.

36. In a system utilizing dielectrically guided waves, two metallicpipes each enclosing a dielectric medium, the respective interiors ofsaid pipes having a dielectric connection between them, shielding meanscomprising an apertured elec'- trode extending wholly across saidconnection, a cooperating electrode on one side or the other of saidapertured electrode, and means including said electrodes forestablishing an energy transfer relation with guided waves in one ofsaid pipes.

GEORGE CLARK SOUTHWORTH.

